The black rectangle at the bottom is the electrolytic capacitor, (+ end to
the left). I was able to bend the leads out and down to holes in the pads.
Round caps may be more difficult to position. You may want to consider drilling
holes and running leads to the pads on the bottom side of the board.

The diode is to the left of the cap, cathode marking to the outside of the
board. It is connected to a pad also holding the input to the 5 volt regulator.

Above the diode, the black, almost circular part is the regulator. If you
face the flat part of the regulator the three pins, left to right are: output,
ground and input. Notice the short jumper wire from the middle lead of the
regulator to the rightmost of the set of holes above the regulator.

The 18 pin socket faces upward and is as high as it can go, leaving the bottom
pads free for other components. The rightmost of these turns out to be ground
and has black wires to it. This orientation of the PIC socket was choosen
so that when the PIC is inserted with the DB9F pointing away from you, the
writing on the PIC is in the normal reading position. This helps warn you
from inserting it backwards.

The pins on the DB9F socket run 1 - 5 top to bottom. Only 3 of these have
wires attached:

DB9F Pin3, (TXD) - yellow wire - goes to a pad just below PIC pin 9, (also
has a 10K resistor and the anode of the diode). This pad was created by cutting
away the trace connecting the bottom portion of the pad. The 10K resistor
goes to PIC pin 4, (MCLR).

DB9F Pin 4, (DTR) - white wire - goes to pad just to left of DB9F pin 1 and
has a 4.7K resistor going to PIC pin 13, (RB7).

DB9F Pin 5, (GND) - black wire - to pad below PIC pin 10. This pad also has
another black wire running to PIC pin 5, (Vss), which has a trace running
to a jumper to the center pin of the 5 volt regulator. Capacitor negative
is also connected to this pad.

Also notice the white jumper from PIC pin 13, (RB7), going to to pad on DB9F
pin 8, (CTS).

A 4.7K resistor on PIC pin 12, (RB6), connects to DB9F pin 7, (RTS).

PIC pin 14, (Vdd) connects by red wires to the output of the 5 volt regulator
and + terminal of the capacitor.

Here is a bottom view of the board:

DB9F pins are 9 - 6 top to bottom, 9 and 6 are open and shouldn't touch any
pads, 7 and 8 have wires inserted, soldered to pads. Other than the board
being jammed between the pins, this is the main support for the board. A
little epoxy between the DB9F and board, (outside the pins), wouldn't hurt.

There are three areas where the traces have been cut and scrapped away between
3 hole pin pads and the pads on the outer edges. Five have been scrapped
away on the right and three at the upper left. Also, on the upper center
left, part of a backwards 'L' shaped pad has been scrapped away to create
two pads, one for the capacitor + lead and the other for the 10K resistor,
yellow wire and diode anode. All unused PIC pins should be soldered to their
pads to make the socket stable.

Use of the Programmer:

The programmer could be plugged directly in a COM port on the computer but
might be hard to reach. I use an Atari joystick extension cable to be able
to plug and unplug the programmer at a convenient location. Just make sure
all the appropriate wires connect through in the cable.

I also find it useful to first place the PIC in a machine pin, 18 pin DIP
socket which is then placed in the programmer socket. Keeping the PIC in
the machine pin socket protects from bending the PIC pins. After a few bends
they tend to break off. I usually insert a screwdriver blade between the
machine pin and programmer socket to separate them, ( unplug the programmer
first).

PIX the Programming Software.

A file called PIX.CFG has to be edited to work with this programmer. Put
in or remove semicolons to decide which options are active. Choose
'Port=Com4',(change to the COM port # you use). Use 'Programmer=Ludi' for
the programmer. I couldn't find much in the way of directions on how to use
the programmer, but it seems pretty straight forward. Load the file using
F3, (sometimes the command line seems to work also). Burn the program into
the PIC with F9.

hello,
I'm trying to program something on a pic16f84a, I've build your com84 programmer. with mplab I create a hex file, that hex file I then load in the pic.exe program. but when I burn the controller I get the following message " blow programm error at 0000h pic = 1000 2826 wanted". Note that I use Ludi on Com1.
Can somebody please help me?
thnx

i vae a problem, I'm trying to make this conntroller, but when I use the 5rd(gnd) and the 3rd(TD) pin, the gnd emits +10v and the RTD emits -10v so i don't know which to adopt as gnd because of the capacitors

I can't download PIX from the website mentioned above.
Could you give me another link?
Have anybody try to program F84A with COM84?Does it work?Or we must modify the circuit?
I've tried to program F84A with PICPRO but it didn't work.
Thanks to you all.

www.piclist.com/techref/piclist/cheapic/COM84.htm
hi,
from the com84 website programmer circuit,
any slight modification can be made to used for
PIC16F84A?
i think the only different is the programming
flash current between PIC16F84 and PIC16F84A.
I'm using MPLAB to output my hex file and plan
to use PIX programming software. this should be
no problem right? i'm using MPASM because it allows
simulation.
thanks in advance

A newer version of the PIX software is available, version 113b. You can find it at http://ftp.iasi.roedu.net/mirrors/ftp.tapr.org/picsig/software/pix113b.zip
Also, the PIC16F84 is pin for pin compatable with the PIC16F84A so you won't need to change the programmer for use with that chip.
Purchasing the components required for this programmer in the UK is available via Maplin Electronics

After you find an appropriate page, you are invited to
your
to this massmind site! (posts will be visible only to you before review)
Just type in the box and press the Post button.
(HTML welcomed, but not the <A tag:
Instead, use the link box to link to another page.
A tutorial is availableMembers can
login
to post directly, become page editors, and be credited for their posts.

Link? Put it here:
if you want a response,
please enter your email address:
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.